C. diff Epidemic: What You Must Know

May 30, 2008 -- While bird flu and MRSA have been making headlines, a dangerous strain of C. diff has been making people sick in 38 U.S. states.

C. diff sickens about a half million Americans every year, and every year the epidemic gets about 10% bigger, CDC medical epidemiologist L. Clifford McDonald, MD, tells WebMD.

Bigger -- and more deadly. The death rate is soaring by 35% a year.

From 1999 to 2004, the bug became four times more lethal, with death rates increasing from 5.7 per million Americans to 23.7 per million Americans in 2004. During one hospital outbreak in Quebec, Canada, the one-year death rate hit 17%.

What's going on? WebMD has answers to these important questions:

How bad is C. diff?

Is C. diff a superbug?

Why are C. diff cases rising so rapidly?

Can you get C. diff from food?

How do you get C. diff?

Who is at risk?

What are the symptoms?

How is C. diff treated?

How is C. diff prevented?

How bad is C. diff?

C. diff disease can range from mild diarrhea to life-threatening colitis. The bug produces toxins that destroy the mucosal lining of the gut.

There are many different C. diff strains circulating in the U.S. But since 2000, one of these strains has gone from a minor player to become the most frequently isolated C. diff strain. The strain has several names. Referring to its genetic fingerprint, the CDC calls it NAP1. In Europe and Canada, it's often called the 027 or BI strain.

The NAP1 strain of C. diff took off shortly after it acquired resistance to fluoroquinolone antibiotics. There's some evidence it may also have acquired some resistance to Flagyl, one of the two antimicrobial agents used to treat it (the other is vancomycin).

Antibiotic resistance isn't the only worrisome thing about NAP1. C. diff normally makes two toxins. The NAP1 strain makes 16 times more toxin A and 23 times more toxin B. And it also makes another toxin, called binary toxin, although it's not yet clear how this toxin affects humans.